Field of the Invention
The present invention generally relates to a button-type electronic shift system, and more particularly, to an electronic shift system that executes a gear-changing operation to a target shift position by the rotation and forward movement of a shift lever.
Description of the Related Art
Generally, in a vehicle equipped with an automatic transmission, hydraulic pressure is adjusted within a preset shifting range based on a cruising speed of the vehicle to allow transmission gears in the range of a target shift position to operate automatically. The automatic transmission generates gear ratios using a hydraulic circuit, a planetary gear train, and friction elements to change gears, and a transmission control unit (TCU) is configured to operate these components.
A shift by wire (SBW) system, which is a vehicle electronic shift system, does not have a mechanical connecting structure, such as a cable, between a transmission and a shift lever unlike mechanical shift systems of the related art. When a sensor value generated in response to the manipulation of an electronic shift lever or button is transferred to the TCU, a solenoid or an electric motor operates in response to an electric signal instructed by the TCU. The operation of the solenoid or the electric motor allows hydraulic pressure to be induced in a hydraulic circuit of each shift position or prevents hydraulic pressure from being induced in the same.
Thus, an automatic transmission based on the SBW transfers a gear-changing intention of the driver in the form of an electrical signal to the TCU in response to the electronic shift lever or button being operated, whereby a gear-changing operation to a driving (D) position, a reversing (R) position, a neutral (N) position, a parking (P) position, or the like may be advantageously facilitated. Since the size of the shift lever may be reduced, a relatively-large space may be advantageously obtained between the driver's seat and the adjacent passenger seat.
Gear-changing systems allowing the driver to change gears using the electronic shift system generally include a lever-type gear-changing system and a button-type gear-changing system. The lever-type gear-changing system is similar to a mechanical shift lever of the related art, which is moved in a forward-backward direction to change gears. In the button-type gear-changing system, a gear-changing operation is performed by pressing or engaging buttons each set to a specific shift position.
However, the above-mentioned lever-type or button-type electronic shift system of the related art has a drawback in that a driver may find the simple gear-changing operation unstimulating. This disadvantageously fails to improve the marketability of the electronic shift system. In addition, the lever-type or button-type electronic shift system of the related art has low reliability, since the gear-changing operation is performed by a single manipulation. Consequently, the possibility of an erroneous manipulation increases.
The foregoing is intended merely to aid in the understanding of the background of the present invention, and is not intended to mean that the present invention falls within the purview of the related art that is already known to those skilled in the art.